Washington and its European allies are preparing a new, tougher deal over Iran's nuclear program, The New York Times reported.

The offer would have Iran ship out some 2000 kilograms of low-enriched uranium, more than two thirds the amount rejected by Tehran under a tentative deal struck in Vienna a year ago, senior officials told the newspaper.

"This will be a first sounding about whether the Iranians still think they can tough it out or are ready to negotiate," a senior American official told the daily. "We have to convince them that life will get worse, not better, if they don?t begin to move."

Another senior US official said Western powers were "very close to having an agreement" to present to Iran.

Iran has yet to respond to a request by EU foreign policy chief Catherine Ashton to meet in Vienna next month.